binding for hdf5 dataset to string

virtdata-lib-hdf5/pom.xml

@@ -53,6 +53,7 @@
                 <directory>src/test/resources</directory>
                 <excludes>
                     <exclude>h5ex_t_float.h5</exclude>
+                    <exclude>hdf5_test_strings.h5</exclude>
                     <exclude>**/*.ivec</exclude>
                     <exclude>**/*.fvec</exclude>
                 </excludes>

virtdata-lib-hdf5/src/main/java/io/nosqlbench/virtdata/library/hdf5/from_long/AbstractHdfFileToVectorType.java

@@ -38,7 +38,7 @@ public abstract class AbstractHdfFileToVectorType {
         int[] sliceDimensions = new int[dims.length];
         sliceDimensions[0] = 1;
         // Do we want to give the option of reducing vector dimensions here?
-        sliceDimensions[1] = dims[1];
+        sliceDimensions[1] = dims.length > 1 ? dims[1] : 1;
         return dataset.getData(sliceOffset, sliceDimensions);
     }
 }

virtdata-lib-hdf5/src/main/java/io/nosqlbench/virtdata/library/hdf5/from_long/to_string/HdfDatasetToStrings.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2023 nosqlbench
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.nosqlbench.virtdata.library.hdf5.from_long.to_string;
+
+import io.nosqlbench.virtdata.api.annotations.Categories;
+import io.nosqlbench.virtdata.api.annotations.Category;
+import io.nosqlbench.virtdata.api.annotations.ThreadSafeMapper;
+import io.nosqlbench.virtdata.library.hdf5.from_long.AbstractHdfFileToVectorType;
+import io.nosqlbench.virtdata.library.hdf5.helpers.EmbeddingGenerator;
+import io.nosqlbench.virtdata.library.hdf5.helpers.EmbeddingGeneratorFactory;
+
+import java.util.function.LongFunction;
+
+/**
+ * This function reads a dataset from an HDF5 file. The dataset itself is not
+ * read into memory, only the metadata (the "dataset" Java Object). The lambda function
+ * reads a single vector from the dataset, based on the long input value.
+ */
+@ThreadSafeMapper
+@Categories(Category.experimental)
+public class HdfDatasetToStrings extends AbstractHdfFileToVectorType implements LongFunction<String> {
+
+    public HdfDatasetToStrings(String filename, String datasetName) {
+        super(filename, datasetName);
+    }
+    @Override
+    public String apply(long l) {
+        long[] sliceOffset = new long[dims.length];
+        sliceOffset[0] = (l % dims[0]);
+        int[] sliceDimensions = new int[dims.length];
+        sliceDimensions[0] = 1;
+        sliceDimensions[1] = dims.length > 1 ? dims[1] : 1;
+        return (String) dataset.getData(sliceOffset, sliceDimensions);
+    }
+
+}

virtdata-lib-hdf5/src/test/java/io/nosqlbench/virtdata/library/hdf5/from_long/to_string/HdfDatasetToStringsTest.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2023 nosqlbench
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.nosqlbench.virtdata.library.hdf5.from_long.to_string;
+
+import io.nosqlbench.virtdata.library.hdf5.from_long.to_list.HdfFileToFloatList;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+public class HdfDatasetToStringsTest {
+
+    @Test
+    public void testHdfFileToVector() {
+        final String[] results = new String[]{
+            "String 1",
+            "String 2",
+            "String 3",
+            "String 4"
+        };
+
+        HdfDatasetToStrings hdfFileToVector = new HdfDatasetToStrings(
+            "/Users/mark.wolters/dev/vec/hdf5_test_strings.h5",
+            "/strings");
+
+        String read;
+        for (int i = 0; i < 4; i++) {
+            read = hdfFileToVector.apply(i);
+            assert (read.equals(results[i]));
+        }
+    }
+}